Enable PAE mode for those CPUs that support it. This allows us to use the

Enable PAE mode for those CPUs that support it. This allows us to use the
NX bit for userland and kernel W^X. Unlike the previous c.2008 PAE
experiment, this does not provide > 4GB phys ram on i386 - PAE is solely
being used for NX capability this time. If you need > 4GB phys, use amd64.

Userland W^X was committed yesterday by kettenis@, and we will shortly
start reworking the kernel like we did for amd64 a few months back to get
kernel W^X.

This has been in snaps for a few days and tested by kettenis and myself
as well.

ok deraadt@, kettenis@